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SoCalMule

What is up with this?

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  Sure could use some advise guys...

  I have found fiberglass muffler packing "plugs" collecting right behind the spark arrester screen on my 450 exc, way too many times. I even road the bike for a few weeks without the screen, thinking that it will just blow out the residual fiberglass (from the fresh repack that was completed 10-15 hours ago). Did I somehow pack the muffler wrong? Maybe I put too much masking tape on to hold the packing in place for ease of reassembling it? I would take the muffler apart... but man, I did such a good job of sealing the muffler with heat rated silicone! Anyone else have had this kind of issue? Is it normal for a fresh repack to shed for a bit? My previous bikes did not have a spark arrester screen system like this one has. The photos show a collection of fiber after an 80 mile desert ride.

Thanks for any help,

The Plugged Mule

P2171920.jpg

P2171918.jpg

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That plug appears to be about the size of a quarter (I am assuming inflation bore its ugly head and only a dime was available!). 

I'll ask the stupid question: why did you repack?  Is this something that needs to be done occasionally?  

Unfortunately I have questions and not answers.

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43 minutes ago, simicrintz said:

That plug appears to be about the size of a quarter (I am assuming inflation bore its ugly head and only a dime was available!). 

I'll ask the stupid question: why did you repack?  Is this something that needs to be done occasionally?  

Unfortunately I have questions and not answers.

 It’s been my experience that to keep optimum performance for the engine that occasionally we should re-pack our mufflers. When a muffler becomes too loud it’s usually a sign that the packing is in need of replacement. One interesting thing is that even with  my muffler  partially blocked my KTM still puts out a lot of horsepower.  I just noticed a performance drop during high demand throttle positions. 

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Sheared off when you were assembling the muffler ?

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Hey Mark, I think your gonna have to take it apart to find out what's up. Some things to look for: Could be something not lined up correctly. Maybe a broken weld. Maybe the perforated tube has split or has a hole in it. That's quite a bit of packing. I think the stock mufflers use o rings to seal the caps. 

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I learn something new every day!  Guess I will be repacking one day.

Mine does have an O ring (took it apart to check it out one day and learned I had to make sure it went back in right!).

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Just now, kkug said:

Sheared off when you were assembling the muffler ?

Thanks kkug, i don’t think that’s it... I was very carfull not to force anything during assembly. This seems to be more like the exhaust gas is creating a resonance and it’s just blasting the insides of the packing out of the muffler and the fibers end up collecting fiber by fiber at the screen. 

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17 minutes ago, amgems said:

Hey Mark, I think your gonna have to take it apart to find out what's up. Some things to look for: Could be something not lined up correctly. Maybe a broken weld. Maybe the perforated tube has split or has a hole in it. That's quite a bit of packing. I think the stock mufflers use o rings to seal the caps. 

Thanks Jim, I agree with you. Was hoping it would just stop on it’s own; that someone had it happen and would say “no problem Mark, just ride it!” 

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Must be the front end open OR packing is too fine and migrating thru screen. Second install is always better.

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19 minutes ago, Bagstr said:

Must be the front end open OR packing is too fine and migrating thru screen. Second install is always better.

That sounds possible Dave. I will dive in to it in the morning. I have a new packing kit that has a separate sock that goes over the screen pipe inside before I wrap it. This should fix it! Thanks so much! I'll post pics of what I find. 

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